Forum: GNU Radio DRM receive

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unknown (Guest)
on 2007-07-18 14:30
(Received via mailing list)
Hi,

did somebody try to use gnuradio for receiving DRM (Digital Radio
Mondiale)?
It seems to me that neither M-QAM demodulation nor the apropriate audio
codec
is presently implemented in gnuradio, however, the DRM program "dream"
has
an option --fileio, which should be able to replace the sound card as
the source
of the IF samples. So I think until everything is available in gnuradio,
it should be possible to do the RF processing with gnuradio (using
basic-rx
and some preamplifier) and feed the frequency-translated data to dream,
which would do the rest.
Does anybody know the format of the data which dream --fileio expects?
Did somebody try this approach before, with/without success?

Best regards,

Jiri
Martin D. (Guest)
on 2007-07-20 01:57
(Received via mailing list)
Jiri Pittner wrote:
> Did somebody try this approach before, with/without success?
Yes I tried it.
Yes it works.

I think the format was complex signed 16 bit integer   (complex short)
(every sample is one signed 16 bit I value and one 16 bit signed Q
value)

You can make these samples with
gr_complex_to_interleaved_short()

you can connect a gnuradio script to the drm receiver app with a pipe
(use mkfifo for that)

pseudocode:

mkfifo my_drm_fifo

./usrp_receive_drm_samples_to_file.py --output-filename=my_drm_fifo
--output-samplerate=samplerate_drm_expects

in another console
./drm --fileio my_drm_fifo


You can also search the gnuradio mailinglist for more info
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